Read HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation key "RealTimeIsUniversal" to see if the Windows guest is expecting RTC set to localtime (not present) or UTC (present and set to 1). See: https://wiki.archlinux.org/title/System_time#UTC_in_Microsoft_Windows See: https://listman.redhat.com/archives/libguestfs/2023-September/thread.html#32556 Reported-by: Lee Garrett Reviewed-by: Laszlo Ersek <lersek@redhat.com>